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United States Patent Gardens, N.Y., assignors to Chas. llfizer & 1G Flue, New York, N.Y., a corporation 10f Delaware No Drawing. Application January 15, 1957 Serial No. 634,151

6 Claims. (CLI60- 468) This invention relates to a valuable class of diesters,

namely diesters of Z-cafboxybicyclo-[2.2.1l-hept--ene- Z-acetic acid which have been found to be particularly useful as plasticizers for vinyl polymers. J n addition,

this invention relates to theprocessior,producingthese diesters.

:More particularly, .the valuable products .ofthepresent esters of itaconic acid, the adduct being of the .tormula:

I om

H \CH2 O no-c b b-on wherein R, and'"R' are alkyl containing up to and i including ten-carbon-atoms. Preferred diesters are those in which R and -R contain frorn four to ten carbon atoms inclusive since they are of lower volatility than those in which .-R and R 'contajnrfrom one to three carbon atoms inclusive. v

The-valuable compounds of the "presentinvention'fhave been found to be excellent*plasticizersyfor vinyl chloride polymers or for copolymers containing 'vinyl'c'hloride or vinylidene chloride as one of the comonomers. For the purpose of using these compounds as plasticizers, they may be admixed with the selected plastic in proportions of 5 to 50% by weight by conventional means such as a Banbury mixer at a temperature of, for example, about 140 C. A subsequently formed sheet of plastic is not only soft and pliable but is also exceedingly tough, the loss of plasticizer under normal conditions of use and exposure to heat and/or light being minimal.

In accordance with the process of the present invention, these valuable compounds are produced by heating a mixture containing from 0.5 to 2 moles of dicyclopentadiene per mole of itaconic acid diester at a temperature of from about 50 to about 180 C. for a time of at least two hours.

Although it is possible to employ cyclopentadiene by mixing the reactants in substantially equimolecular proportions and heating at a temperature from about 0 to about 50 C., the preferred process for making the compounds of the present invention utilizes dicyclopentadiene as a starting material. By the use of dicyclopentadiene, the difiiculties of preparing cyclopentadiene from the commercially available dicyclopentadiene are avoided. In the case of preparing the nonesterified compounds corresponding to the diesters of the present invention, it is essential to start with cyclopentadiene in view of the fact that itaconic acid isomerizes at the temperatures required to provide cyclopentadiene in the reaction mixture by depolymerization of dicyclopentadiene. The foregoing is explained in concurrently filed copending application, Serial No. 634,153.

invention .are the adducts of cyclopentadiene and the diice The itaconic acid diester starting material of -t;he;present invention wherein R and R' are identical maybe made, as is known, by conventional"esterification procedures. The 'itaconic acid diester starting material of the present invention wherein f-R and R are dissimilar can also be prepared by methods 'known to those skilled in the art. For example, an equimolar portion of it aconic acid may be reacted with one mole of an alkanol containing .up to ten carbon 'atoms .to -;produce .a zfiacarbo- .alkoxy v itaconate. This itaconate can ,..in-.:tur n, the ,converted .to .an acid-chloride ;by reaction with .thionylschlo- ;ride :or other .halogenating agents, and-the resulting acid chloride converted to .a. diester byreaction with :a .segond portion of a dissimilar alkanol :containing upsto ten carbon atoms. As stated above these dieste'rs are of the formula:

-o--'o-oR o e- 0R H2 wherein R and R" are zalkyl containing :up '-to' and including ten carbon atoms. I w 1315 The reaction mixture of the present invention-requires the presence of at least 0.5 mole of dicyclopentadiene per mole of itaconic acid .diester in order to obtain a high yield of the desired end product and avoid the necessity of removing excess diester of itaconic acid aften'completion of the reaction. Excess xlicyclopenta- :diene up to .twozmoles may :bertoleratedzinzorder to permit .adeqnate cyclopentadiene 111.0 the formed .during :reaction at a gl'ate permitting suitable reaction :rates :between :the

,diester and cyclopentadiene. Upon completion .oftthe reaction, excess .dicyclopentadiene or .itsrmonomer may .be removed by distillation.

The process .of the present invention may be. .carried .outat temperatures ranging from about 5.0 to .abontil C the preferred temperature being from about ,13i0-. l60 C. At temperatures within this .range'reaction "tirnes of at least about two hours are required in'ordei'"to produce substantial yields of the desired end product. Reaction times of about 15 to 20 hours are preferred since they represent time conditions necessary to obtain highest yields compatible with the economies of heat requirements. Reaction times as high as 25 hours have been employed but are generally not necessary.

When employing the proportions, temperatures and reaction times set forth above and in the absence of a solvent, the yields obtained of high purity product are of the order of about 75 to This yield may be improved slightly by employing a polymerization inhibitor such as hydroquinone, diphenylamine, methylene blue, etc. In a preferred application of the invention the reaction is carried out in an inert atmosphere, for example, nitrogen, since the presence of the inert atmosphere decreases the possibility of side reactions.

For the purpose of recovering the desired end product of the present invention, the preferred method includes distillation of excess cyclopentadiene dimer or monomer under reduced pressure.

The foregoing description of the present invention and the following examples are for the purpose of illustration only and not limiting to the scope thereof which is set forth in the claims.

EXAMPLE I 2-carbomezhoxybicyclo [2.2.1 -hept-5-ene-2-acetic acid methyl ester A mixture of 2.0 moles of dimethyl itaconate, 1.5 moles of dicyclopentadiene and 1.0 g. of hydroquinone was heated in a nitrogen atmosphere at a temperature of 140 to 150. The mixture was held at this temperature for seventeen hours and was then distilled. After a forerun of unreacted dicyclopentadiene, there was col- .lected at 87'to 100 C. (0.6 mm.) 1.6 moles (80%) of the desired dimet hyl ester; n =1.4778. I

. Analysis.-Calcd. for C H O Carbon, 64.3; hydrogen, 7.19. Found: Carbon, 64.3; hydrogen, 7.16.

EXAMPLE II Z-carbethoxybicyclo [2.2.1l-hept-S-ene-Z-acetic acid methyl ester A mixture of 1.0 mole of a-ethyl-fi-methyl-itaconate,

0.5 mole of dicyclopentadiene and 0.2 g. of hydroquinone ',was heated at 130 C. in a nitrogen atmosphere for fifteen hours. At the .end of this time volatile material was removed by distillation and the desired product obtained jin 75% yield by distillation in vacuo. 1

EXAMPLE III Z-carbodecyloxybicyclo [2.2.11-hept- -ene-2-acetic acid decyl ester A mixture of 1.0 mole of didecyl itaconate and 1.0 mole of dicyclopentadiene was maintained at a temperature of 150 for twenty hours. At the end of this time 'volatile material, was removed by distillation and the desired material obtained in 82%, yield by distillation :in'vacuo.

' EXAMPLE IV Z-carbo-n-butoxybicyclo [2.2.1l-hept-S-efie-Z-acetic acid-n-butyl ester EXAMPLE V A mixture containing 33% by weight of di-n-butyl itaconate and 67% by weight of a copolymer of vinyl chloride and vinyl acetate containing of the chloride was fluxed on a rubber mill at a steam temperature of C. It was observed that the mixture fluxed readily during mixing, although with considerable fuming. The di-n-butyl plasticizer was found to be compatible with the resin, and the product prepared w tough, pliable and essentiafil'y colorless.

What is claimed is:

1. A product of the formula:

alkyl containing up to and including ten carbon atoms.

2. The product of claim 1 wherein R and R' are alkyl containing from four to ten carbon atoms inclusive.

3. 2 carbomethoxybicyclo-[2.2.1]-hept-5-ene-2-acetic acid methyl ester.

4. Z-carbethoxybicyelo-[2.2.1J-hept-S-ene-Z-acetic acid methyl ester.

5. 2 carbodecyloxybicyclo-[2.2.1J-hept-S-ene-Z-acetic acid decyl ester.

6. 2 carbo-n-butoxybicy clo-[2.2.1]-hept-5-ene2-acetic acid-n-butyl ester.

References Cited in the file of this patent UNITED STATES PATENTS 2,264,354 Alder et a1. Dec. 2, 1941 2,311,261 Staff Feb. 16, 1943 2,752,361 Robitschek et al 'June 26, 1956 OTHER REFERENCES Organic Reactions, IV, 14, 15, 55. J. Wiley, 1948. Elsevier, 12A, 978 (1948). Beilstein, 9, 578 (1949). 

1. A PRODUCT OF THE FORMULA: 